A carbon nano-tube field emission display (CNT-FED) uses screen-printing processes and field emission display technology to achieve the capability of flat display panel from the conventional field emission display. It not only reserves the image quality of cathode-ray tube display but also provides the advantage of saving energy and small volume. Moreover, the above advantages combine with the low conductive electric field, the high emission current density and high stability of the carbon nano-tube simultaneously, so the CNT-FED can be a novel flat display with the advantages of low driving voltage, high luminous efficiency, no view angle problem, low energy consuming, large size and reduced cost.
Referring to FIG. 1, which shows the schematic view of a conventional field emission display wit a triode structure, the triode structure is a common structure for improving the electron energy, the luminous efficiency and reducing the control voltage. The luminous principle of a conventional carbon nano-tube field emission display is shown in FIG. 1, the conventional CNT-FED includes a substrate 101 and a cathode electrode 102 formed on the substrate 101; a carbon nano-tube layer formed on the surface of the cathode electrode 102 as an electron emitter 103; a dielectric layer 104 formed adjacent to the cathode electrode and a gate 105; wherein a plurality of electrons arc induced from the cathode electrode 102 by the gate 105, and the direction of the electron current is shown as the direction of the arrowhead in FIG. 1. After that, an anode plate 107 is provided on the opposite side of the cathode electrode 102, and a phosphor layer 106 formed on one side of the anode plate 107 is bombarded by the electron beam, and red, green and blue colors are emitting through the glass substrate 108 to outside.
Referring to FIG. 1, wherein the anode plate 107 of the triode structure is provided to improve the energy of the electrons; the cathode electrode 102 is the electron emitter, the gate 105 is provided to attract the electrons. In conventional triode structure, the shapes of most of the gates 105 are hole shaped, and the carbon nano-tube emitter 103 is in the hole of the hole shaped gate 105. The advantage of the hole shaped gate 105 is the electron beam easy control, but the drawback is the electron beam easy diffusing to all-directions. In order to narrow the diffusion of the electrons, the hole shaped gate 105 needs to be made very small, extremely smaller than 10 μm.
Referring to FIG. 2, which is a plan schematic view showing a first hole shaped gate structure of a conventional carbon nano-rube field emission display (Korea Samsung), the triode carbon nano-tube structure is formed on a substrate 101 and the electrons of the carbon nano-tube emitters 103 formed on the cathode in the gate holes 22 are induced by the gates 105, and then they are accelerated by the anode plate 107 to bombard the phosphor 106 fanned on the anode plate (not shown in the figure) and this structure illustrated above is a conventional Spindt type structure. Because the electrons of the carbon nano-tube emitters 103 induced by the gate holes 22 diffuse to all-directions, it produces the cross-talk phenomenon.
Referring to FIG. 3A through 3C, a schematic view showing a second hole shaped gate structure of a conventional carbon nano-tube field emission display is illustrated. The carbon nano-tube emitters 103 are provided in the holes of a plurality of gates 105, the plurality of gate holes are isolated with each other by a dielectric layer 104, a plurality 0f cathode electrodes 102 is provided on the substrate 101, and an anode plate 107 is provided opposite to the cathode electrodes 102. The electric field is formed by the cathode electrode 102 and the anode plate 107 and the electrons are induced from the cathode electrode 102, so the electrons of the electron emitters 103 are induced by the gates 105 to bombard the phosphor 106 formed on the anode plate 107.
FIG. 3B is a cross sectional schematic view along the X-direction in FIG. 3A. In the figures, the gate holes formed by the gates 105 and the electron emitters 103 are obvious, and the electrons of the electron emitters 103 are induced from the cathode electrodes 102 by the gates 105 to bombard the phosphor 106 formed on the anode plate 107. Although the hole shaped gates 105 can control the electron beam, the electron beam easily diffuses to all-directions after leaving the gate holes (as the arrowheads show). As FIG. 3C shows a cross sectional schematic view along the Y-direction in FIG. 3A, the direction of the arrowhead is the direction of the electron beam. Although the electron emitters 103 are around by the gates 105, the electrons of the electron emitters 103 induced by the gates 105 still diffuse to all-directions.
There is one other conventional emitter design, which is a wedge-shaped emitter, and the emitting mechanism is the same as the Spindt type structure illustrated above. However, in the same field emission array (FEA), the field emission area for the wedge-shaped emitter is larger than, the conventional Spindt type structure. But the electron beam of the wedge-shaped emitter structure still diffuses to bombard the close pixels on the anode plate, and produces the cross-talk phenomenon in X and Y directions.
Due to the problems of the conventional FED and the difficulty of the screen-printing technology for forming the carbon nano-tube field emission display, a carbon nano-tube field emission display having strip shaped gates is provided according to the present invention. The present invention is using the side electron force of the gates to attract the electrons to control the electron diffusion direction confined in die same direction, and achieves the object of high luminous efficiency